oSIST prEN 1337-7:2018
(Main)Structural bearings - Part 7: Spherical and cylindrical PTFE bearings
Structural bearings - Part 7: Spherical and cylindrical PTFE bearings
This document specifies rules for the design, manufacture and testing and of spherical and cylindrical sliding PTFE bearings.
It is applicable to spherical and cylindrical sliding bearings with an included angle up to 60° for spherical and 75° for cylindrical sliding bearings.
This document will be used in conjunction with the relevant parts of this standard series.
Lager im Bauwesen - Teil 7: Kalotten- und Zylinderlager mit PTFE
Dieses Dokument legt Regeln für die Bemessung, Herstellung und Prüfung von Kalotten- und Zylinderlagern mit PTFE fest.
Das Dokument gilt für Kalotten- und Zylinderlager mit einem enthaltenen Winkel von bis zu 60° für Kalottenlager und 75° für zylindrische Gleitlager.
Dieses Dokument wird in Kombination mit den anderen relevanten Teilen dieser Normenreihe verwendet.
Appareils d’appui structuraux - Partie 7 : Appareils d’appui cylindriques sphériques comportant du PTFE
Le présent document spécifie les règles de conception, d’essai et de fabrication d’appareils d’appui cylindriques et sphériques comportant du PTFE.
Il s’applique aux appareils d’appui cylindriques et sphériques avec un angle inscrit allant jusqu’à 60° pour les appareils d’appui sphériques et 75° pour les appareils d’appui cylindriques.
Ce document sera utilisé conjointement aux parties pertinentes de cette série de normes.
Konstrukcijska ležišča - 7. del: Sferična in cilindrična PTFE ležišča
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
oSIST prEN 1337-7:2018
01-marec-2018
.RQVWUXNFLMVNDOHåLãþDGHO 6IHULþQDLQFLOLQGULþQD37)(OHåLãþD
Structural bearings - Part 7: Spherical and cylindrical PTFE bearings
Lager im Bauwesen - Teil 7: Kalotten- und Zylinderlager mit PTFE
Ta slovenski standard je istoveten z: prEN 1337-7
ICS:
91.010.30 7HKQLþQLYLGLNL Technical aspects
oSIST prEN 1337-7:2018 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN 1337-7:2018
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oSIST prEN 1337-7:2018
DRAFT
EUROPEAN STANDARD
prEN 1337-7
NORME EUROPÉENNE
EUROPÄISCHE NORM
January 2018
ICS 91.010.30 Will supersede EN 1337-7:2004
English Version
Structural bearings - Part 7: Spherical and cylindrical PTFE
bearings
Lager im Bauwesen - Teil 7: Kalotten- und
Zylinderlager mit PTFE
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 167.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations
which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 1337-7:2018 E
worldwide for CEN national Members.
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Contents Page
European foreword . 4
1 Scope . 5
2 Normative references . 5
3 Terms , definitions and symbols . 5
3.1 Terms and definitions . 5
3.2 Symbols . 6
4 Types of spherical and cylindrical bearings . 7
4.1 General . 7
4.2 Spherical bearings . 7
4.3 Cylindrical bearings . 8
5 Materials . 9
6 Design . 9
6.1 General . 9
6.2 Design verification for curved sliding surfaces . 9
6.3 Eccentricities . 10
6.3.1 General . 10
6.3.2 Eccentricity due to frictional resistance . 10
6.3.3 Rotation . 11
6.3.4 Lateral forces . 11
6.3.5 Eccentricity along the cylindrical axis . 11
6.4 Compressive stress verification . 11
6.5 Rotation capacity . 12
6.6 Separation of sliding surfaces. 12
6.7 Design details . 12
6.7.1 Curved PTFE sheets . 12
6.7.2 Backing plates . 12
6.7.3 Restraining ring . 13
6.8 Combination with other bearings or elements . 13
7 Testing . 13
8 Manufacturing, assembly, tolerances, marking and labelling . 14
9 Transport, storage and installation . 14
10 In service inspection . 14
11 Maintenance . 14
12 AVCP . 14
Annex A (informative) Reduced area for curved sliding surfaces . 15
A.1 General . 15
A.2 Modelling assumptions . 15
Annex ZA (informative) Relationship of this European Standard with Regulation (EU)
No.305/2011 . 18
ZA.1 Scope and relevant characteristics . 18
ZA.2 System of Assessment and Verification of Constancy of Performance (AVCP) . 20
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ZA.3 Assignment of AVCP tasks . 20
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oSIST prEN 1337-7:2018
prEN 1337-7:2018 (E)
European foreword
This document (prEN 1337-7:2018) has been prepared by Technical Committee CEN/TC 167
“Structural bearings”, the secretariat of which is held by DIN.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 1337-7:2004.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association, and supports essential requirements of EU Regulation 305/2011.
For relationship with EU Regulation 305/2011, see informative Annex ZA, which is an integral part of
this document.
prEN 1337, Structural bearings, consist of the following 8 parts:
— Part 1: General;
— Part 2: Sliding elements;
— Part 3: Elastomeric bearings;
— Part 4: Roller bearings;
— Part 5: Pot bearings;
— Part 6: Rocker bearings;
— Part 7: Spherical and cylindrical PTFE bearings;
— Part 8: Guide bearings and Restraint bearings.
The major technical changes are listed below:
— Complete technical and editorial revision of the document; it is not possible to list all implemented
changes to this edition of EN 1337-7.
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1 Scope
This document specifies rules for the design, manufacture and testing and of spherical and cylindrical
sliding PTFE bearings.
It is applicable to spherical and cylindrical sliding bearings with an included angle up to 60° for
spherical and 75° for cylindrical sliding bearings.
This document will be used in conjunction with the relevant parts of this standard series.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
prEN 1337-1:2018, Structural bearings — Part 1: General
prEN 1337-2:2018, Structural bearings — Part 2: Sliding elements
prEN 1337-5:2018, Structural bearings — Part 5: Pot bearings
EN 1993 (all parts), Eurocode 3: Design of steel structures
3 Terms , definitions and symbols
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1.1
backing plate
metallic component which supports sliding materials
3.1.2
cylindrical PTFE bearing
bearing consisting of a backing plate with a convex cylindrical surface (rotational element) and a
backing plate with a concave cylindrical surface between which a PTFE sheet and the mating material
form a curved sliding surface (see Figure 3)
Note 1 to entry: Cylindrical PTFE bearings are also used in combination with flat sliding elements and guides to
form free or guided bearings (see Figure 4)
3.1.3
guide
sliding element which restrains a sliding bearing from moving in one axis
3.1.4
lubricant
special grease used to reduce the friction and wear in the sliding surfaces
5
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3.1.5
mating surface
hard smooth metallic surface in contact with the sliding material (PTFE, CM1 or CM2)
3.1.6
Polytetrafluoroethylene
PTFE
thermoplastic material used for its low coefficient of friction
3.1.7
sliding materials
materials which form sliding surfaces
3.1.8
sliding surface
combination of a pair of flat or curved surfaces of different materials which allow relative
displacements
3.1.9
spherical PTFE bearing
bearing consisting of a backing plate with a convex spherical surface (rotational element) and a backing
plate with a concave spherical surface between which a PTFE sheet and the mating material form a
curved sliding surface (see Figure 1)
Note 1 to entry: Spherical PTFE bearings are also used in combination with flat sliding elements and guides to
form free or guided bearings (see Figure 2).
3.2 Symbols
The most frequently occurring symbols are defined below. Those that are local, and unique to a
particular clause, are defined at their first appearance.
A contact area 2
mm
d diameter, diagonal, depth mm
e eccentricity mm
f tensile or compressive strength MPa
l contact length of the PTFE in cylindrical bearings mm
N axial force; force normal to principal bearing surface N; kN
r radius of the curved contact surface mm
t thickness mm
V transverse or shear force N; kN
µ coefficient of friction —
α angle of rotation rad
β deviation angle from vertical axis of the line of action of the applied load
γ partial factor —
λ ratio, coefficient —
θ included angle of the spherical or cylindrical surface °
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Indices
b backing plate
max maximum —
min minimum
red reduced
tot total —
x, y, z coordinates —
PTFE Polytetrafluoroethylene
4 Types of spherical and cylindrical bearings
4.1 General
Spherical and cylindrical bearings consist of a concave part which supports a convex part. Rotations are
enabled by the convex element sliding along the curved contact surface with the concave element. The
forces in z-direction are transferred through the convex part by the sliding element into the concave
part. The bearing can be used in inverted position also. Figure 1 shows a typical cross section of a fixed
spherical PTFE bearing.
Figure 1 — Spherical PTFE bearing
4.2 Spherical bearings
Spherical bearings comprise a spherical convex and a spherical concave part and are fixed bearings
which allow rotations about any axis.
With flat sliding elements spherical bearings form free bearings (see Figure 2 a)). With guides the free
bearing becomes a guided bearing (see Figures 2 b) and 2 c)). With a restraining ring the free bearing
becomes a fixed bearing (see Figure 2 d)).
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Figure 2 — Spherical PTFE bearing combined with flat sliding elements
4.3 Cylindrical bearings
Cylindrical bearings comprise a cylindrical convex and a cylindrical concave part and are guided
bearings which allow rotations about the cylinder axis and movements along it. With guides the guided
bearing (see Figure 3 a)) becomes a fixed bearing (see Figure 3 b)). Cylindrical bearings are susceptible
to restraining moments about the transverse axis of the cylinder.
Key
a) without end stops for displacements in y-direction
b) fixed by end stops and sliding surface
Figure 3 — Cylindrical PTFE bearings
With flat sliding elements the fixed cylindrical bearings form free bearings (see Figure 4 a)). With
guides the free cylindrical bearing becomes a guided bearing (see Figures 4 b) and c)).
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Key
a) Free for displacements in any directions
b) Guided by an internal guide for displacement in x-direction
c) Guided by external guides for displacement in x-direction
Figure 4 —Cylindrical PTFE bearings combined with flat sliding elements
5 Materials
The materials used shall be in accordance with prEN 1337-2:2018.
6 Design
6.1 General
prEN 1337-1:2018 applies.
This clause gives requirements for the design of components which are specific to spherical and
cylindrical bearings and which are in addition to those given in prEN 1337-2:2018 and comprise the
design of the curved sliding surfaces and the design of the backing plates.
Secondary effects due to the action of the restraints shall also be considered.
The selected material shall be verified in accordance with the principles given in the relevant parts of
the EN 1993 series, e.g. EN 1993-1-10.
6.2 Design verification for curved sliding surfaces
Forces and moments acting on the curved sliding surface due to friction resistance, externally applied
horizontal loads and the rotated condition of the bearing shall be taken into account when determining
the resulting total eccentricity e of the axial force N .
tot z,d
The eccentricity is the perpendicular distance between the crossing point “A” and the z-axis.
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Figure 5 — Verification scheme for the curved sliding surface (example)
6.3 Eccentricities
6.3.1 General
This Clause gives methods for calculating the relevant eccentricities.
Other eccentricities than those given in 6.3.2 to 6.3.5 can co-exist, e.g. stiffness effect from end
diaphragms.
If several eccentricities occur in a cross-section under consideration, they need to be added.
6.3.2 Eccentricity due to frictional resistance
6.3.2.1 Curved sliding surfaces
In the presence of rotational movements, in both cylindrical and spherical bearings, an internal moment
occurs due to the frictional resistance.
Regardless of whether the bearing has one or two surfaces, the associated eccentricity e is given in
1
Formula (1).
erµ⋅ (1)
1 max
6.3.2.2 Sliding surfaces with external guides and restraining rings
For the spherical bearings of the type shown in Figures 2 c) and 2 d), rotational movements produce an
eccentricity which affects only the adjacent structural members (i.e. plinth, beam, etc.) and the
anchoring devices, which shall be determined with Formula (2).
V
d
ec⋅µ (2)
2 max⋅
N
d
Where
c clearance between sliding components (difference in width between key and keyway)
10
=
=
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6.3.3 Rotation
In all the types of bearings with two sliding surfaces, a rotation angle α produces an eccentricity e of
3
the vertical load on the curved surface which shall be determined with Formula (3).
e=α⋅+rb (3)
( )
3
where
b represents the distance between the cross-section under consideration and the sliding surface
(see Figure 5).
The occurrence of e depends on whether the curved PTFE sheet is either attached to the convex or
3
concave backing plate and whether the value α is greater or lesser than μ as well as on whether the
bearing clearance is performing its function effectively in the case of guided bearings.
Because of the uncertainty concerning the actual values of α and μ as well as the effective bearing
clearance can entail, it is suggested that e superimposed on e should in any case be taken into account
3 1
since a precise analysis cannot be carried out.
For the combination of the eccentricities e and e , only e due to permanent rotation shall be taken
1 3 3
into account.
6.3.4 Lateral forces
Lateral forces result from horizontal actions and the friction resistance of the other bearings in the
structure.
In bearings where lateral forces are transmitted by guides or restraining rings, the eccentricity in the
curved sliding surface is equal to zero.
In bearings of the fixed type with only one sliding surface and in the guided spherical bearing, the
horizontal load V produces an eccentricity given by Formula (4) (see also Figure 5):
d
V
d
e ⋅+rb (4)
...
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